Based on the information in the text and the graph, Tarhan et al. cou… | Verbal SAT Question

Distribution of Silica Cements and Grains Associated with South Australian Ediacara Casts by Ge/Si Ratio

Ge/Si Ratio	Cements (approximate)	Grains (approximate)
<2.0	30%	80%
2.0–2.5	12%	11%
2.5–3.0	14%	4%
3.0–3.5	15%	2%
3.5–4.0	12%	2%
4.0–4.5	8%	1%
4.5–5.0	5%	1%
>5.0	5%	0%

Silica cements associated with casts of soft-bodied marine organisms from the Ediacaran period (circa 538–635 million years ago) are plausibly attributable to one of two phenomena: rapid postmortem preservation of the organisms via precipitation of cements from silica-rich oceans or cement precipitation via high-pressure reactions long after the organisms were preserved by some other means. Recognizing that such reactions generally result in cements with germanium/silicon (Ge/Si) ratios lower than those of silica grains recovered from the same portion of sandstone, Lidya Tarhan et al. investigated silica cements and grains associated with Ediacaran soft-bodied casts at a site in South Australia.

Based on the information in the text and the graph, Tarhan et al. could most reasonably draw which conclusion?

The range of Ge/Si ratios is larger for the cements than for the grains, which suggests that the cements are likely the result of high-pressure reactions that occurred long after the organisms were preserved by some other means than precipitation from a silica-rich ocean.

The distribution of Ge/Si ratios indicates that a portion of the cements could have precipitated via high-pressure reactions, which suggests that organisms at the site were less likely to have been preserved via rapid precipitation from a silica-rich ocean than Tarhan et al. hypothesized.

The distribution of Ge/Si ratios of the cements and grains is largely inconsistent with the cements having precipitated via high-pressure reactions, which implicitly lends support to the idea that the organisms at the site were quickly preserved by cement precipitation from a silica-rich ocean.

The total number of cement samples is much lower than the total number of grains precipitated via high-pressure reactions, which suggests that rapid precipitation from silica-rich oceans could account for the preservation of the site’s organisms.